RU2732619C1 - Method of brittle materials crushing - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method of grinding brittle materials which can be used in production of construction materials, ore-dressing, food and glass industry. Method comprises impact action of working member on brittle environment, wherein each impact member of working member, along with their combined rotation is set degree of mobility around proper axes, located equidistant to axis of rotation. At that, additionally to each impact element of the working member, the ripple rotation speed is forced, and its rotation axes—forced precession motion with nutation.

EFFECT: method provides higher degree of grinding efficiency.

1 cl, 1 tbl, 7 dwg

Description

The invention relates to the field of production of building materials, mining, food and glass industries, and can be used in machines designed for crushing fragile materials, solid waste or their fine crushing by crushing.

The known method of grinding fragile material [RU 2148434 C1, "METHOD OF GRINDING FRAGILE MATERIALS", IPC В02С 13/10, publ. 05/10/2000] which includes the supply of the material into the working cavity, the impact of grinding bodies on it and the unloading of the crushed material, in which grinding is carried out by direct action on the pieces of crushed material simultaneously splitting, shearing, crushing and grinding forces created between the movable and stationary surfaces, when In this case, the working cavity formed by them decreases in the direction of movement of the material to the size of a given size of crushed particles, and unloading is carried out through one or more unloading slots, radially, and the given size of particles is regulated and determined according to the formula specified in the description. The invention makes it possible to create a continuous high-intensity grinding process in one stage until ground particles are obtained no more than any given size.

The disadvantages of this method include: the lack of the possibility of fine grinding, since a given particle size is determined by the gap formed by the movable (rotor) and fixed surfaces of the crusher, and the size of this gap is structurally limited; a sharp decrease in productivity if fine grinding is necessary, since the working cavity (working zone) formed by the movable and stationary surfaces creating destructive forces decreases along the movement of the material to the size of the given size of the crushed particles; uneven granulometric composition, since pounded, split, cut and crushed particles enter the unloading slot at the same time; the sizes of the initial particles are determined not only by the size of the working cavity at the inlet, but also by the wedging angle, at which the particle is entrained by the rotor and crushed.

The known method of layered grinding of rocks [RU 2353428 C2, "METHOD FOR LAYERED CRUSHING OF ROCKS", IPC В02С 4/10, publ. 04/27/2009], which includes the creation of normal compressive forces on the rock pieces by working surfaces. In the process of processing, a complex stress state of the pieces of the processed material is created, for which the latter are placed between converging working working surfaces moving in the direction of convergence of the working surfaces with different linear speeds, then gradually increasing the value of normal compressive forces, bringing the stress state of the material to close to the ultimate strength on compression, at the same time pieces of rock are additionally loaded with forces in the direction of convergence of the processing surfaces, prevent the rotation of the said pieces of material, at the same time act with tangential forces on the upper layers of the material until they peel off, then under the total action of these forces break the pieces into smaller pieces and repeat the process until the desired particle size of the material. EFFECT: increased yield of flat, flake-shaped product.

The disadvantages of this method are: a sharp decrease in productivity when it is necessary to obtain a finely dispersed material, since its dispersion decreases with a decrease in the gap (decrease in the working area) between the rotating working surfaces that create destructive forces; uneven granulometric composition, if necessary, coarse grinding, since in the destruction zone both radial (splitting) and tangential (abrasion and shear) forces act on the material, which give a different fractional composition of the material during its destruction; the sizes of the initial particles are determined by the wedging angle at which the particle is carried away by the working processing surfaces and is crushed.

The known method of grinding materials, implemented in the grinder of bulk materials [RU 2528456 C1, "HAMMER CRUSHER", IPC В02С 13/14, publ. 09/20/2014], taken as a prototype. The method consists in the fact that the crushed rock is fed into the crushing chamber, where a forced impact is exerted on it by the working body, in which each of its striking elements, in addition to their joint rotation, is given a degree of mobility around their own axes located equidistantly to the axis of rotation, thereby crushed, and then removed from this zone. Moreover, the feed of the crushed material is carried out from top to bottom, and removal through a sieve, while the output fraction after crushing is determined only by the parameters of the sieve.

The disadvantages of this method are: a sharp decrease in productivity when it is necessary to obtain a finely dispersed material, since the volume of the working zone is small, and the dispersion decreases due to an increase in the number of impacts on the crushed material in this volume; the inability to adjust the degree of grinding of the material during operation; uneven particle size distribution, since upon impact on the crushed body, a heterogeneous fractional composition of the material is formed during its destruction.

The technical problem is to increase the efficiency of the method for crushing brittle materials, which consists in: ensuring the possibility of obtaining a more uniform particle size distribution; in increasing productivity during fine grinding by increasing the area of the contact patch at the moment of impact on the ground rock; in the possibility of adjusting the process of cracking, and hence the degree of grinding.

The technical problem posed is achieved by the fact that in the method of crushing fragile materials, including the impact of the working body on a fragile medium, in which each of its striking elements, in addition to their joint rotation, set the degree of mobility around their own axes located equidistantly to the axis of rotation, according to the invention, velocity pulsations rotation of the working body, and its axes forcibly set precessional motion with nutation.

The essence of the invention is illustrated by drawings, where

in fig. 1a) shows the first instantaneous position of the point ТУ1 of the hammer impact at pulsations of the speed (- ω ₁ ) in the direction opposite to the rotation ω _{0 of the} working body

in fig. 1b) shows the movement of the instantaneous position of the hammer impact point from ТУ1 to the midpoint ТУ0 when changing the direction of the velocity pulsation ω ₀ (second position)

in fig. 1c) shows the displacement of the instantaneous position of the hammer impact point from ТУ0 to the ТУ2 point at pulsations of the speed (+ ω ₁ ) of the working body in the direction of its parallel rotation ω ₀ (third position)

in fig. 2a) shows a diagram (in accordance with the prototype) of the destruction of a fragile material upon impact without hesitation of the working (grinding) body (two positions of the hammer);

in fig. 2b) shows increased cracking when the hammer moves in one blow in the vertical plane (View B), which is set by precessional motion with nutation of the working body axis;

in fig. 3 shows the effect of pulsations of the rotational speed of the working body on the expansion of the crack formation area. Top view (View A), distribution of shock load in the horizontal plane during one hammer blow;

in fig. 4 shows the formation of an increased instantaneous cracking surface area during one hammer impact due to the complex forced vibration displacement of the hammer impact point in the vertical and horizontal planes;

in fig. 5 shows a photo of an experimental crusher for controlled dimensional dispersion of fragile media;

in fig. 6 shows the samples to be ground;

in fig. 7 shows the samples before and after crushing.

The method is carried out as follows (see Fig. 1): each striking element (hammer) (4) of the working body, along with joint rotation at a speed ω _{0, is} forcibly set with a certain amplitude of the pulsation of the rotation speed of ± ω ₁ , providing a deviation of the trajectory of the shock element (hammer) (8): to move the point of impact from ТУ0 to ТУ1 along line (5) at ω ₀ -ω ₁ (see Fig. 1b), then back to point ТУ0 (see Fig. 1a), and then to point ТУ2 at ω ₀ + ω ₁ (see Fig. 1c). This movement is carried out cyclically, since fluctuations in the rotation speed ω _{0 are} carried out during the entire operation time of the rotation drive. Simultaneously with this oscillatory movement, the impact point is forced to vibrate in the vertical direction along the sinusoid (7) due to precessional motion with nutation by means of an inertial rotary vibration drive, the rotor of which is rigidly connected to the hammer in the vertical direction. As a result of the combined action of such vibrational displacements, the impact point is always on a sinusoid, the extreme positions of which change in accordance with the movement of the impact point from ТУ0 to ТУ1 and back, and then from ТУ0 to ТУ2.

With uniform rotation (in accordance with the prototype) of the working body with hammers, hinged, along the trajectory (6), with the possibility of rotation in the horizontal plane relative to the attachment point, the impact in the direction (9) is provided at one point of the surface of the material to be crushed (see Fig. 2a), forming the main crack (10), and then splitting it.

According to the proposed method, along with the pulsations of the rotation speed ω ₀ ± ω _1, each hammer (4) is forced to have vertical oscillatory movements (11) (see Fig. 2b), obtaining three such points: impact point 1, with the hammer in the middle position; impact point 2, when moving the hammer up; and impact point 3, when moving the hammer down. In fact, this is an array of points lying on a line from point 2 to point 3 in the vertical direction. As a result of such a distributed impact, accordingly, there will be several centers of cracking - at points 1, 2 and 3, respectively, where: 10 - main cracking at 1 point of impact; 12 - additional cracking at the 2nd point of impact; 13 - additional cracking at the 3 point of impact.

In the horizontal direction, vibrational displacements of the positions of the instantaneous points of application of the hammer impact force on the surface of the crushed body are carried out by pulsating the axis rotation speed with a frequency of ± ω ₁ . With horizontal displacement of the position of the point of application of the impact force (see Fig. 3) in the case of ω ₀ -ω _1, we obtain the point TU1, in which a crack is formed. Then, at ω ₁ = 0, the position of the point of application of the impact force moves to the point ТУ0 in which a crack is also formed, and then, at ω ₀ + ω _1, to the point ТУ2, which coincides with the point ТУ1, providing additional cracking and destruction of the material. At the same time, as can be seen from the above-described set of actions, when changing the vibration parameters, it became possible to change the position of the point of application of the impact force (distribute it over the surface) and, accordingly, control the process of cracking, which will lead to a change and stabilization of the size of the chipped particles.

Joint displacement position of the point of application of impact forces about the center of the rolling hammer (U _K) forms a region of distribution of these points in the vertical and horizontal direction (see. FIG. 4) is an enlarged surface cracking (D), where the designated position the impact force application points for vertical displacement, these are points 1, 2 and 3, respectively, with the lines of movement of point 2 (5-2) and point 3 (5-3), and the positions of the points of application of the impact force during horizontal movement, respectively, ТУ0, ТУ1 and ТУ2 with their movement lines ( 13) for point ТУ0, (14) for point ТУ1 and (15) for point ТУ2. This forms an extended fracture area. Since a whole array of points is formed, providing controlled cracking, the grinding process becomes predictable and, accordingly, the particle size distribution is stabilized.

The advantages of the above method include the provision of the effect of the distribution of the instantaneous impact load on an area significantly exceeding the contact area of the hammer with the rock with a single impact (as in the prototype), and, accordingly, a multiple increase in the network of cracks. Such crushing leads to a significant increase in productivity and, at the same time, the dimensional uniformity of the resulting particles (i.e., controlled cracking is provided).

In other words, an increase in the working zone of the hammer is achieved, since, in addition to rotation, the latter performs a precessional movement with nutation and speed pulsation. And this allows you to significantly increase productivity in fine grinding and increase the degree of grinding of components.

The new set of actions makes it possible to regulate the degree of crushing during the process with continuous supply and discharge of the crushed material, by controlling the parameters of oscillatory movements. As a result, a more uniform particle size distribution of the product is obtained.

The method was applied in the design of a crusher for crushing minerals, which was tested in laboratory conditions. The task of the tests was a comparative determination of the productivity and the degree of grinding of the device in the presence of only the rotational motion of the hammers and when additionally imparting pulsations of the rotational speed and precessional motion with nutation of the rotational axis to them. To create such a movement, the crusher (Fig. 5) is equipped with a planetary inertial vibration exciter [A.S. 1664412, 21.07.1991], which provides a smooth change in the parameters of the oscillations, and to ensure the pulsation of the speed, a valve-inductor electric drive (VIP) was used [Sergeev Yu.S., Sandalov V.M., Karpov G.E. Modeling of a valve-inductor electric vibration drive. - Bulletin of SUSU, power engineering series, 2017, V. 17, No. 4. S. 90-98]. The pulsations of the speed ω ₀ ± ω _{1 are} controlled by the electronic control system, in accordance with the required law. The regulation of the parameters of the pulsations of the rotation frequency is carried out by changing the angle of on and off of the corresponding winding of the electric motor and positional switching is applied using PWM control, which allows not only setting the required laws of pulsations, but also completely turning them off. Vibrations, like speed pulsations, can also be turned off. According to the parameters of crushing force, productivity and degree of grinding, the effectiveness of the application of the above method was determined.

The tests were carried out for various minerals with a Mohs hardness from 1 to 6 (marble, serpentine, lemesite). Samples of different sizes were previously prepared (Fig. 6), which were subjected to grinding according to the claimed method. To determine the crushing force and productivity when grinding selected materials with different mechanical properties, each type of mineral was fed into the working area in the form of samples of certain sizes, starting with a smaller size, while the total volume of material samples supplied at a time was constant and amounted to 0.01 m ² ... Crushing in all tests was carried out in one stage, namely, the size of the outlet slot remained unchanged. At the same time, the vibration frequency was gradually increased (by increasing the axial pressing force of the vibration exciter rotor) and the value of the frequency (270 rad / sec) and the vibration amplitude were recorded, with the remaining settings unchanged (the rotational speed of the working body with hammers was 52 rad / sec). The values of the crushing force were calculated and the graphs of the dependence of this force on the frequency and amplitude of oscillations were constructed. To determine the performance during the test was recorded during grinding batch one volume of sample (0.01 m ^2), and the value determined by blunt force previously determined was compared with graphs and mechanical properties used minerals. According to the ratio of the sizes of the crushed samples before and after grinding, the degree of crushing was determined (Fig. 7). The indicative test results are summarized in the table.

After testing the crusher operating according to the proposed method, the same samples were crushed during the same period of time, but with the vibration exciter turned off and without the pulsation of the speed of the working body (hammer rotation frequency - 52 rad / sec). The test results for this crushing are shown in the same table.

Comparison of the granulometric composition showed its higher uniformity when using the proposed method.

Thus, the proposed method used in the crusher increases productivity, the degree of grinding and the uniformity of the particle size distribution. Tests have shown the efficiency of the method and its effectiveness.

The proposed method can be implemented in installations for the production of building materials, mining, food and glass industries, and can be used in machines designed for crushing fragile materials or their fine crushing by crushing, as well as in the processing of waste of the same materials.

Sources of information taken into account

1. Patent for invention RU No. 2148434 C1 Method of crushing fragile materials, publ. 05/10/2000 bul. №13 Tsoraev U.M.

2. Patent for invention RU No. 2353428 C2 Method for layered crushing of rocks, publ. 04/27/2009, bul. No. 12, Malygin. Yu.N.

3. Patent for invention RU No. 2528456 C1 Hammer crusher publ. 09/20/2014 Bulletin No. 26 "Closed joint-stock company" Engineering company tekhneks ".

4.A.S. 1664412 USSR, MKI. В06В 1/15. Method of excitation of circular vibrations and a device for its implementation / S.G. Lakirev, Ya.M. Khilkevich, S.V. Sergeev. - No. 4414912 / 24-28; declared 04.24.88; publ. 07.23.91, Bul. No. 27. - five.

5. Sergeev Yu.S., Sandalov V.M., Karpov G.E. Modeling of a valve-inductor electric vibration drive. - Bulletin of SUSU, power engineering series, 2017, V. 17, No. 4. S. 90-98.

Claims (1)

A method of crushing fragile materials, including the impact of the working body on a fragile medium, in which each impact element of the working body, along with their joint rotation, is given a degree of mobility around its own axes located equidistant to the axis of rotation, characterized in that additionally, each impact element of the working body is forced to rotation speed with pulsation, and its rotation axis - forced precessional motion with nutation.

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